1. Field of the Invention
The present invention generally relates to a method, system and software product used in the area of mechanical computer-aided engineering design and analysis, more particularly to method and system for prescribing rigid body orientations in finite element analysis.
2. Description of the Related Art
Finite element analysis (FEA) is a computerized method widely used in industry to model and solve engineering problems relating to complex systems such as three-dimensional non-linear structural design and analysis. FEA derives its name from the manner in which the geometry of the object under consideration is specified. With the advent of the modern digital computer, FEA has been implemented as FEA software. Basically, the FEA software is provided with a model of the geometric description and the associated material properties at each point within the model. In this model, the geometry of the system under analysis is represented by solids, shells and beams of various sizes, which are called elements. The vertices of the elements are referred to as nodes. The model is comprised of a finite number of elements, which are assigned a material name to associate with material properties. The model thus represents the physical space occupied by the object under analysis along with its immediate surroundings. The FEA software then refers to a table in which the properties (e.g., stress-strain constitutive equation, Young's modulus, Poisson's ratio, thermo-conductivity) of each material type are tabulated. Additionally, the conditions at the boundary of the object (i.e., loadings, physical constraints, etc.) are specified. In this fashion a model of the object and its environment is created.
Rigid body is defined as a body whose parts all have a fixed relationship to each other. Rigid bodies have been included in the finite element analysis software to model mechanical parts that is rigid or at least relatively rigid compared to other parts to be analyzed. However, main features of finite element analysis software have been focused on various elements (e.g., solids, shells, beams). Rigid bodies are added to complement the main features. As a result, many of the operations on the rigid bodies are approximations with assumption of small displacements. For example, to prescribe the orientation of a rigid body, the calculations are incremental based, thereby the results are incorrect for arbitrary orientations.
It is therefore desirable to have a new improved method and system for prescribing rigid body orientations in a finite element analysis.